Pneumatic tires for automobiles, aircraft and other vehicles have traditionally been inflated by compressed ambient air. Generally, compressed air works well with bicycle tires, tractor tires and even standard automobile tires run at relatively low speeds where exacting tire balance and consistent tire pressure is not critical. In the case of uses such as race cars, dragsters, and high altitude aircraft, compressed ambient air is not a satisfactory medium for inflating tires for a variety of reasons.
When compressed air is introduced into a tire via a compressor open to the ambient atmosphere, water vapor and other impurities are introduced into the tire in the same proportions as they occur in the ambient air. With all of the moisture and other impurities present, air volume in the tire fluctuates fairly widely with temperature, particularly due to the moisture changing from liquid to vapor form and from vapor to liquid form as temperatures in the tire change. In addition, tire pressures may vary from tire to tire which may also possess deleterious results.
Pressure of air in tires inflated with compressed ambient air will change about 1 psi for every 10 degree Fahrenheit change in temperature. Thus, a tire inflated at 60 degrees Fahrenheit will be substantially under inflated at 20 degrees due to the combined effects of temperature in reducing gas pressure and moisture condensing out of the air within the tire. Conversely, as temperatures increase to 90 degrees Fahrenheit, the tire will be substantially over inflated due to the water being vaporized and the attendant increase in air pressure due to temperature. These under or over inflation conditions can adversely affect rolling friction of tires on pavement, thus decreasing gas mileage. Tire wear is also substantially increased when tires are not inflated to a manufacturer's recommendations. Handling problems may be aggravated by tire pressure differential between front and back tires and/or side to side.
Water vapor within tires may also induce rust within steel belted radials, which further reduces tire life. Furthermore water vapor introduced into a tire in a high altitude jet airplane, for example, will condense and then freeze thereby forming ice crystals which generally fall to the bottom of the tire as it lies stationary in the wheel well of the airplane. When an airplane lands, the tires must accelerate virtually instantly from rest to more that 150 miles per hour. As a result, ice crystals in the tire can create a substantial imbalance. As the tire accelerates, the ice crystals are thrown around the rolling tire by centrifugal force, leading to further imbalance, increased internal wear, and an increased likelihood of tire blow-outs. In the case of race cars and dragsters, since the water vapor introduced into the tire condenses and vaporizes at unpredictable times, condensed water within the tire lags behind the column of air within the tire as the tire is rapidly accelerated. Furthermore, as the race car tires spin at high speed, considerable heat builds up in the tires themselves, thus considerably increasing the internal tire pressure due to the expansion of the water vapor.
In order to eliminate these problems, operators and owners of race cars, space shuttle transport vehicles, earthmoving and mining equipment and commercial and military high altitude aircraft often inflate their tires with compressed nitrogen or another generally non-reactive and non-combustible gas such as argon or sulfur hexafluoride. Nitrogen is an ideal gas for such a purpose since it is chemically non-reactive, non-combustible, non-flammable and non-corrosive. Furthermore, when dry, nitrogen gas is relatively stable in volume through a wide range of temperatures. For example, the specific volume of a quantity of dry nitrogen gas at 1 atmosphere of pressure varies less than 13% in a range of −10 degrees F. to +116 degrees F. Thus, the use of nitrogen to inflate a pneumatic tire offers a large reduction in fluctuations of internal tire pressure due to temperature variations over those which occur when moisture laden compressed ambient air is used. Furthermore, since nitrogen is stored in pressurized tanks under controlled conditions, the nitrogen gas can be dried and purified as it is placed into the tank, thus minimizing moisture and other impurities transferred into the tire.
However, when new or repaired tires are first placed on a wheel, they must be inflated under high pressure to get the tire bead to seat on the wheel rim. In order to accomplish this compressed ambient air must be used. Once the tire is inflated and properly seated on the wheel rim, the compressed air is bled off via a tire's Schrader spring loaded valve, and a source of compressed nitrogen is then attached to the tire valve to re-inflate the tire. With this method, the tire's internal pressure is simply returned to ambient pressure before being filled with nitrogen. This air at ambient pressure in the tire having a quantity equal to the internal volume of the tire. Along with the quantity of air left in the tire, moisture and other gaseous impurities are present in the tire in the same proportion as they are found in the ambient atmosphere. When the dry, purified nitrogen is introduced into the tire under pressure, it mixes with the air, moisture and other impurities already present in the tire as the tire is inflated. The inflated tire is thus filled with a quantity of air including attendant moisture and other impurities and a larger quantity of nitrogen, thus repeating, albeit at a reduced level, the problems associated with the use of ambient compressed air.
It is clear that a need exists for a tire inflation apparatus and method which avoids these problems of the prior art. Such a tire inflation apparatus should preferably inflate tires with compressed, purified and dried gas, such as nitrogen, to a manufacturer's recommended tire pressure while minimizing or eliminating moisture and other impurities in the tire.
In order to obviate the deficiencies in the prior art, it is an object of the present subject matter to present a novel portable gas delivery device. The device includes a gas source and supply line connected to a controller. The device also includes a gas delivery line comprising a manifold with a plurality of outlets in fluid communication with each other. A gas delivery line is operably connected to the controller and a plurality of extension lines with engagement chucks are operably connected to the outlets. the controller controls the supply of gas to the gas delivery line and controls a relief valve for venting the gas delivery line. The device also includes a sensor and a processor connected the controller and sensor which accepts user inputs. The controller, manifold and processor are affixed to a stand.
It is also an object of the present subject matter to present a novel method of ensuring pressure equalization between multiple tires during evacuation and inflation of the tires. The method includes providing a plurality of supply hoses in fluid communication with each other, attaching each of the supply hoses to a corresponding valve stem located on the tires, and supplying pressurized gas from a gas source to the tires via the supply hoses. The method further includes monitoring and controlling a gas characteristic of the pressurized gas in the of the supply hoses to inflate the tire to a predetermined pressure so as to ensure pressure equalization between each of the tires.
It is a further object of the present subject matter to present a novel method for evacuating and inflating a pneumatic tire. The method including opening a relief valve on a gas supply hose to vent the supply hose to atmosphere, closing the relief valve, and supplying pressurized inert gas from a gas source to the tire through the gas supply hose to inflate the tire with a first predetermined amount of inert gas. The method also includes opening the relief valve to vent the gas supply hose to atmosphere, closing the relief valve, and supplying pressurized inert gas from the gas source to the tire through the gas supply hose to inflate the tire with a second predetermined amount of inert gas.
These objects and other advantages of the disclosed subject matter will be readily apparent to one skilled in the art to which the disclosure pertains from a perusal or the claims, the appended drawings, and the following detailed description of the preferred embodiments.